1. Field of the Invention
The present invention relates in general to the field of light amplification, and more particularly to the field of automated laser tuning.
2. Description of Related Art
Chirped Pulse Amplification (CPA) is very useful for producing ultra short-duration high-intensity pulses for use in high peak power ultra short pulse laser systems. CPA increases energy of an ultra short laser pulse while avoiding optical amplifier damage and excessive nonlinear distortion. In this technique, a duration of the pulse is first increased by dispersing the ultra short laser pulse temporally as a function of wavelength (a process called “chirping”) to produce a chirped pulse. The chirped pulse is then amplified and recompressed to significantly shorten its duration. Lengthening the pulse in time reduces the peak power of the pulse and, thus, allows energy to be added to the pulse without incurring excessive nonlinearities or reaching a damage threshold of the pulse amplifier and optical components. An amount of pulse amplification that can be achieved is typically proportional to the amount of pulse stretching and compression. Typically, the greater the amount of stretching and compression, the greater the possible pulse amplification.
A CPA system typically comprises an optical stretcher, an optical amplifier, and an optical compressor. The optical stretcher and optical compressor are ideally configured to have equal but opposite dispersive properties to perfectly compensate for one another to minimize the pulse width of an amplified optical pulse. The optical stretcher may comprise a bulk diffraction grating, an optical fiber, a fiber grating, or other dispersive optical elements. Optical fiber-based dispersive optical elements are generally not used in the optical compressor because the peak power of an optical pulse within the optical compressor is generally larger than an optical fiber's nonlinear threshold. Therefore, bulk diffraction gratings are generally used in optical compressors due to the ability of bulk diffraction gratings to handle larger optical power levels than optical fibers.
Any material through which an optical pulse propagates, such as a waveguide in an optical amplifier, may add dispersion to the optical pulse. This additional dispersion may not be compensated by a perfectly matched optical stretcher and compressor pair. In addition, dispersion properties of the components of an ultra short pulse amplification system may be sensitive to temperature as well as minute variations in the parameters and physical configuration of the system components. Therefore, adjustment of various parameters and positions of the system components may be required on a regular and periodic basis to maintain desired system operation. Traditionally, this has made hands-on operation and adjustment by knowledgeable and experienced laser system experts required to properly use ultra short pulse amplification systems.